This invention relates to call forwarding between systems in a telecommunications network, and, more particularly, to an apparatus and method for activating and deactivating call forwarding from a subscriber number of a first system to a predetermined subscriber number of a second system, utilizing messages transmitted from a subscriber station operating in the second system.
Developments in wireless systems technology have resulted in a variety of systems being available for use by system subscribers. Many different types of wireless systems now exist or have been proposed at the concept stage. These wireless systems include conventional cellular and PCS systems that allow a system user to make and receive phone calls through a mobile station while roaming in the large geographic area covered by the system. These wireless systems also include cordless or wireless residential systems that allow system users to make and receive phone calls through a mobile handset while within a smaller coverage area, such as within a residence or an office building.
Cellular and PCS systems include base stations that are dispersed in locations through the coverage area of the system, which may be an area such as the area of a few cities or a state, or a larger area. These base stations each provide a radio interface between the system and the mobile stations as the mobile stations roam through the system. The base stations are connected to and controlled by one or more mobile switching centers (MSCs) that communicate with the base stations to provide the intelligent functions necessary for call routing and other operations of the system. The cellular/PCS system is most often connected to a public switched telephone network (PSTN) to provide phone connections to general public service.
A cordless or wireless residential system typically operates with a personal base station (PB) providing a radio interface between the system and the mobile handset. The PB can provide a range of intelligent functions, depending on the system type. Depending on the size of the system, different numbers of base stations are used. For example, if the cordless or wireless residential system is located in a residence, only one PB may be necessary. The PB of a cordless or residential system may be connected to a PSTN through a single wireline connection. If the cordless or residential wireless system covers an office building, more than one PB, one on each floor for example, may be necessary. When more than one PB is used, the PBs may be connected to the PSTN through a private branch exchange (PBX) if necessary.
Networks containing Cellular or PCS systems combined with cordless or wireless residential systems (cellular/PCS wireless esidential networks) have recently been proposed in the telecommunications industry. In a cellular/PCS wireless residential network, a system subscriber is assigned a dual mode mobile station (DMM) that may be operated in either a wide area cellular/PCS system or the subscribers residential cordless system. In this type of network each of the cellular/PCS and residential cordless system s is typically connected to the public switched telephone network(PSTN).
In the cellular/PCS wireless residential network the subscriber may roam about the coverage area of the cellular/PCS system, while using the handset to initiate and receive calls over the radio channels of the cellular/PCS system. The subscriber may also move into the coverage area of the subscriber""s residential cordless system and make and receive calls over the residential cordless system radio channels. Selection between which of the two systems the subscriber operates in may be done manually by the subscriber, or automatically within the network. For example, the cellular/PCS residential system could be designed so the DMM is switched from communications on the cellular/PCS radio channels air interface to communications on the cordless system radio channels when signal strength levels received at the handset on the radio channels of the residential cordless system become greater than a certain threshold level.
In a typical cellular/PCS residential system a subscriber may be assigned two phone numbers within the PSTN. One phone number would be assigned as the subscribers cellular/PCS number, and the other phone number would be assigned to the wireline connection to the residential cordless system PB as the residential number. Calls made to the cellular/PCS n umber a re directed to the cellular/PCS system and calls made to the residential number would be directed to the residential cordless system. If the subscriber is actively using the DMM within the cellular/PCS system, i.e., is registered in the cellular/PCS system, and a call is made to the cellular/PCS number, the call is directed to the DMM within the cellular/PCS system. Calls directed to the residential cordless number are received at the PB or PBs of the cordless system. If the subscriber""s DMM is active in the cordless system and a call is made to the PB number, the subscriber""s DMM will be alerted.
Since a cellular/PCS residential subscriber moves between and operates in both systems, the subscriber may desire that he be able to receive calls made to the phone number assigned for one system at the phone number assigned for the second system, when the subscriber is operating in the second system. For example, the subscriber may desire to receive calls made to his Cellular/PCS number, as well as to the residential number, when operating in the residential cordless system. This may be the case if the cellular/PCS number is used as a business number by the subscriber and the subscriber wishes that calls to the business number reach the subscriber when the subscriber is in his residence and the subscriber""s DMM is operating in the residential cordless mode.
In one possible solution, the dual mode subscriber could implement desired call forwarding from the cellular/PCS number to the residential number before leaving the cellular PCS system from the DMM using presently existing call forwarding technology and techniques. However, once activated, the call forwarding would remain active until deactivated from the DMM in the cellular/PCS system and could not be controlled from the residential cordless system.
In another possible solution, call forwarding from the cellular/PCS number to the residential number may be automatically activated by a signal sent through the PSTN upon each registration of the DMM with a PB in the residential cordless system. The call forwarding could then be cancelled upon registration of the DMM in the cellular/PCS system. This solution suffers from the shortcoming that the dual mode subscriber could not deactivate the call forwarding from the cellular/PCS number to the residential number that would occur while operating in the residential system, until the DMM was registered again in the cellular/PCS system. There also may be situations in which the dual mode subscriber does not wish to receive forwarded calls.
The above solutions also suffer from another shortcoming in that they do not allow the dual mode subscriber the option of deactivating activated call forwarding from the cellular/PCS number to the residential number upon certain select conditions. For example, the dual mode subscriber may desire that activated call forwarding be deactivated when the DMM switches from the cordless residential mode to the cellular/PCS mode of operation but not when the DMM is powered down or loses communication with the residential cordless system.
The present invention provides an apparatus and method, in a network having a first and a second system, for activating and deactivating call forwarding from a predetermined subscriber number of the second telecommunications system to the subscriber number of a first telecommunications system, utilizing messages transmitted from a subscriber station operating in the first telecommunications system. In the method and apparatus taught by the invention, a first message including a first data field having at least two states is transmitted to the first system from the subscriber station. The first message is transmitted upon initiation of communication between the subscriber station and the first system. A determination is then made within the first system as to whether or not the data field is in a first state. If it is determined that the data field is in the first state, call forwarding from the subscriber number of the second telecommunications system to the subscriber number of the first system is activated. If the data field is in a second state, call forwarding from the subscriber number of the second telecommunications system to the subscriber number of the first system is not activated. An indication of at least one type of subsequent event upon which the user of the subscriber station desires to deactivate call forwarding may also be included in the first message. The information on the at least one type of subsequent event included in the first message may be stored in the first system as call forwarding deactivation conditions. The first message may also be transmitted during operation of the subscriber station in the first system to change the present call forwarding status and deactivation conditions.
A second message may also be transmitted to the first system from the subscriber station when communications between the subscriber station and the first system cease. The second message contains an indication that an event has occurred in the system. If no second message is received by the first system within a predetermined time period after communications between the subscriber station and the first system cease, the first system may determine that a loss of communications event has occurred. A determination is then made as to whether or not the operator of the subscriber station desires to deactivate call forwarding from the subscriber number of the second telecommunications system to the subscriber number of the first system upon the occurrence of the event that the second message indicates occurred, or upon a loss of communications event. If the operator of the subscriber station desires to deactivate call forwarding upon occurrence of the event and call forwarding has been activated, the call forwarding is deactivated.
The method and apparatus of the invention allows a system subscriber who operates subscriber stations in both the first and second systems to easily determine and control activation and deactivation of call forwarding to have calls routed from the subscriber""s number in the second system to the subscriber""s number in the first system when operating a subscriber terminal in the first system. The method and apparatus removes the need for the subscriber to activate and deactivate call forwarding while operating within the second system before beginning, or after terminating, operation of the subscriber terminal in the first system to achieve the same result. The method and apparatus of the invention is an improvement over methods used in dual mode networks in which call forwarding from a second number to a first number is always automatically activated without user choice upon registration of a dual mode subscriber station in the first network.
In an embodiment of the invention, the method and apparatus is implemented within a telecommunications network having a first and a second system, and a dual mode mobile station (DMM) capable of operating in either the first or second system. A first subscriber number is assigned to the DMM in the first system and a second subscriber number is assigned to the DMM in the second system. The second subscriber number may be the wireline number to which a personal base station (PB) of the first system is connected. The user of the DMM may operate the DMM in either the first or second mode by switching manually between the modes, or the DMM may switch between the first and second modes automatically dependent upon the system in which the DMM is located.
When the DMM begins operation in the first mode in the first system, a registration message is transmitted to the first system from the DMM. The registration message includes a field including a registration bit that is set to one or zero. The registration bit may be selectively set by a user of the DMM from a menu selection. The first system receives the registration message and determines the state of the registration bit. If the registration bit is set to a predefined state, the first system then initiates transmission of a signal to the second system through the network. In response to receiving the signal, the second system then activates call forwarding from the second subscriber number to the first subscriber number. After activation of call forwarding, calls to the second subscriber number will be routed to the first subscriber number. Deactivation event data stored in the first system may also be transmitted in the registration message when the DMM begins operation in the first mode. The deactivation event data may include a user termination bit, a power down bit, and a loss of communication bit. The state of each of these bits indicates whether the first system should signal the second system upon the occurrence of the event, so that activated call forwarding from the second subscriber number to the first subscriber number is deactivated.
When operation of the DMM in the first mode ends, a deregistration message may be transmitted to the first system from the DMM. The deregistration message includes a field including a power down bit and a user termination bit. The power down bit indicates that the deregistration message is transmitted as the result of a power down of the DMM while in the first mode. The user termination bit indicates that the deregistration message is the result of the user terminating the first mode operation for the DMM by, for example, manually switching to the second mode of operation. Upon receiving the deregistration message, the first system determines what event resuted in the deregistration. Alternatively, if no deregistration message is received when operation of the DMM ceases in the first system, the first system may determine that a loss of communications event has occurred. Based on the deactivation event data stored in the first system, the first system then determines whether or not to transmit a signal to the second system to initiate deactivation of call forwarding from the second subscriber number to the first subscriber number.